Tag: homo antecessor

Human footprints up to one million years old discovered at Happisburgh, Norfolk

Footprints left by small group of adults and children are oldest discovered outside Africa

Human footprints dating to between one million and 780,000 years old have been reported on the beach of the coastal village of Happisburgh, Norfolk (pronounced ‘Hazeborough’), and are the earliest-known direct evidence for the presence of humans in northern Europe. The footprints briefly emerged at low tide in May 2013, having being exposed by rough seas.

Within a fortnight, they had vanished again – but not before a team led by Nick Ashton from the British Museum had obtained plaster casts and 3d images. A total of 152 footprints were recorded, of which twelve yielded complete outlines suitable for analysis. It is thought that these twelve footprints represented five individuals ranging in height from 0.93 to 1.73 m (3 ft. 0 in. to 5 ft. 8 in.), suggesting the presence of both adults and children. It has been suggested that the Happisburgh hominins are related to Homo antecessor (‘Pioneer man’), a human species known from Sierra de Atapuerca in northern Spain during the period between 1.2 million and 800,000 years ago (Ashton, et al., 2014).

Early humans from this period are broadly categorised as Homo erectus. In Europe, Homo erectus was later replaced by the larger-brained Homo heidelbergensis, which might have been the forerunner of the Neanderthals in Europe and modern humans in Africa.

The Happisburgh footprints are the earliest direct evidence for humans in Britain, but tools used by these first Britons have been coming to light since 2005, when 700,000-year-old flint artefacts were reported from Pakefield in Suffolk (Parfitt, et al., 2005). In 2010 even earlier flint artefacts were reported from Happisburgh, estimated to be at least 780,000 years old, and probably older (Parfitt, et al., 2010). Previously, the earliest uncontested evidence for humans in northern Europe dated to no earlier than around 500,000 years ago (Parfitt, et al., 2005).

Analysis of animal remains suggests the Happisburgh people occupied the edges of forests at what was then an estuary of the River Thames, and lived towards the end of a warm interglacial period. It is not certain when the interglacial occurred, but there were warm periods from 866,000 to 814,000 years ago, and from 970,000 to 936,000 years ago (Parfitt, et al., 2010).

Britain was at this time connected to the mainland and lying on the southern edge of the forests of northwestern Europe. The climate was similar to that of today and while comfortable by British standards, it would have been chilly for those used to a Mediterranean or African climates. It remains unclear whether expansion into northern latitudes with lower winter temperatures required human physical adaptation, seasonal migration or developments in technology such as hunting, clothing, the use of shelters and the control of fire (Parfitt, et al., 2005; Parfitt, et al., 2010; Roberts & Grun, 2010).

Introduction:Homo heidelbergensis, or “archaic Homo sapiens”, is the name given to the large-brained hominins that appeared in Africa 600,000 years ago and migrated into Europe and possibly Asia. It is conventionally regarded as having given rise to modern humans in Africa and the Neanderthals in Europe.

The type specimen is the Mauer Mandible (Mauer 1), a virtually-complete lower jaw recovered from fluvial beds near the village of Mauer, in south-west Germany. The find was made on 21 October 1907 by a gravel-pit worker named Daniel Hartmann and described the following year by Professor Otto Schoetensack of the University of Heidelberg. The Mauer Mandible has been dated to 500,000 years old.

Until about ten years ago, the rather unsatisfactory term “archaic Homo sapiens” was used to describe any mid-Pleistocene hominin that wasn’t Homo erectus, Homo sapiens, or a Neanderthal. The latter was usually classified as a subspecies of Homo sapiens, i.e. H. s. neanderthalensis, but they are now generally regarded as a separate species. Consequently “archaic Homo sapiens” is itself regarded as a separate species, with the 1907 name Homo heidelbergensis having seniority under the rules of taxonomy.

As Manzi (2004) notes however this is no more than a revision of the old paradigm, with the substitution of a grade “archaic Homo sapiens” with a clade, Homo heidelbergensis, accompanied by the recognition of three distinct species, i.e. H. heidelbergensis, H. neanderthalensis and H. sapiens, with corresponding speciation events between the Middle and Late Pleistocene in Africa and Eurasia.

Whether or not Homo heidelbergensis is a genuine species or simply a grade of “Version 3.0 human” containing several species remains controversial.

Key Fossils:Kabwe (Broken Hill), Zambia: Skull and several postcranial bones including a femur and a tibia (Broken Hill 1). It was found in an iron and zinc mine in Broken Hill, Northern Rhodesia (now Kabwe, Zambia) in 1921 by a Swiss miner named Tom Zwiglaar. Dating is uncertain, but probably between 700,000 and 400,000 years old. It has a cranial capacity of around 1100cc and was originally described as Homo rhodesiensis.

Lake Ndutu, Tanzania: a 400,000 year old cranium, found in 1973, with an estimated cranial capacity of 1100cc.

Bodo, Middle Awash, Ethiopia: a 670,000-600,000 year old cranium found in 1976 by a survey headed by Jon Kalb. Cranial capacity is 1300cc.

Petralona, northern Greece: Skull discovered in cave system in 1960, dated 250,000 – 150,000 years old, with a cranial capacity of 1200cc.

La Caune de Arago, Tautavel in southern France: isolated teeth, cranial, mandibular and fragmentary postcranial remains belonging to at least four adults and three children, dated to approximately 450,000 years old. The distorted Arago 21 cranium has an estimated capacity of 1150cc.

Mauer, Germany: the Mauer Mandible, as mentioned above.

Steinheim, Germany: a distorted but nearly complete cranium found in a gravel pit 1933 by Karl Sigrist. It is believed to be 350,000-250,000 years old. The cranial capacity is 1100cc.

Swanscombe, England: three skull fragments belonging to the same individual recovered between 1935 and 1955; believed to be 300,000-200,000 years old and popularly known as Swanscombe Man, though now thought to be female. The cranial capacity has been estimated at 1325cc.

Dali, Shaanxi Province, China: a 250,000 year old cranium discovered by Shuntang Liu in 1978, with a cranial capacity of 1120cc.

Jinniu Shan: cranium, vertebrae, ribs, pelvis, patella and limb bones discovered in 1984. The cranial capacity is 1300cc and the remains are believed to be 250,000 years old.

Description:Manzi (2004) selects the Middle Pliocene fossils from Kabwe, Petralona and Dali fossils as being typical of Homo heidelbergensis. They have a “transitional aspect” between earlier and more recent hominins which include both primitive and derived traits. Primitive or “archaic” features include a heavily-built cranial structure with massive brow ridges; crests in the temporo-occipital region, including erectus-like occipital and angular tori; a low and antero-posteriorly elongated cranial vault; a protruding and large facial skeleton; and the absence of a modern chin. These traits are however reduced in comparison to Homo ergaster/erectus.

The main derived feature is that the general shape of the cranial vault is consistent with increased brain-size. The frontal is less receding than it is in earlier hominins; the parietal profile is more convex along the mid-sagittal plane and less angled in coronal sections; and the occipital squama is more vertical and arched.

The cranial capacity is typically between 1100-1300cc, around 90% of that of modern humans, a considerable increase on that of Homo erectus/ergaster.

Affinities to other hominins:The view that this species evolved in Africa about 600,000 years ago, then migrated into Europe, and that the two lineages led to respectively Homo sapiens and the Neanderthals, is probably as convincing as any of the alternatives.

Homo antecessor (known only from Spain) has recently been touted as ancestral to Homo heidelbergensis, suggesting that either the latter was a European species that later migrated back into Africa, or that Homo antecessor evolved in Africa.

Another possibility is that African and European Homo heidelbergensis are different species, with the Bodo Cranium an early example of the former. On this view, the African species would take the name originally assigned to the Bodo Cranium, Homo rhodesiensis. However the sudden increase in brain size to 90% of the modern average seen in the fossil record at around 600,000 years ago, after remaining more or less static at 65% during the previous 1.2 million years, does suggest a punctuated event which in turn suggests a single species.

Just about all that can be safely said at the present time is that our understanding is very incomplete!

Technology:Homo heidelbergensis is associated with the same Acheulian (Mode II) technology as that originated by Homo ergaster 1.65 million years ago; however later Acheulian hand-axes are thinner, more symmetric and more extensively trimmed. Some authorities describe this technology as “Late Acheulian”. It is possible that its appearance is connected with the emergence of Homo heidelbergensis and is a product of this species greater cognitive abilities.

Homo cepranensis is the name proposed for a hominid skullcap found near the Italian town of Ceprano in 1994 by archaeologist Italo Biddittu. Unfortunately it was shattered by a bulldozer during highway construction immediately before its discovery. On the basis of regional correlations and a series of absolute dates, the age of the Ceprano hominid is estimated to range between 800,000 and 900,000 years.

It shares many features with skull caps of Homo erectus including a massive shelf-like brow ridge, extremely thick skull walls, sharply-angled occipital region and a small internal volume, estimated at 1057cc. Had it been discovered in eastern Asia, it might well have been assigned to H. erectus (Scarre (2005)).

Interpretation is difficult due to the lack of material. Manzi et al (2001) point out that affinity with the contemporary Homo antecessor might be expected but unfortunately among the nearly 80 fossil pieces that have been found so far, none is directly or adequately comparable with the Ceprano specimen, at least in terms of completeness (as for some temporal bone fragments) or age at death (as in the case of the juvenile frontal TD6-15). It is possible that further examples of H. antecessor will eventually be recovered, and that these will reveal affinities to H. cepranensis.

However Cameron & Groves (2004) have suggested that this species originated in Eurasia, with a later Eurasian Homo erectus population moving into Western Europe about one million years ago before eventually becoming extinct. Clarke (2000) claims the Ceprano specimen has affinities to the Olduvai hominid OH9 (1.2 million years old). OH9 and OH12 (700,000 years old) have been considered to represent “classic” (i.e. Eurasian) specimens of Homo erectus and may represent an expansion of this species back into Africa from Eurasia. On this picture, then, Homo cepranensis is seen as a representative of a European deme of Homo erectus that was associated with migrations “Into Africa”.

Homo antecessor (“Pioneer Man”) is the name given to an extinct human species known from just two sites in the Atapuerca Hills of Northern Spain – Gran Dolina and Sima del Elefante. The remains were discovered by Eudald Carbonell, Juan Luis Arsuaga and J. M. Bermúdez de Castro.

The initial discoveries were made at the Gran Dolina Cave, Layer TD6 between 1994 and 1995. The find comprised over 90 bone fragments including 18 skull fragments, 4 partial jaws, 14 teeth, 16 vertebrae, 16 ribs, 20 bones from the hands and feet, 2 wrist bones, 3 collar bones, 2 lower arm bones, a thigh bone and 2 knee-caps from a minimum of 6 individuals, all of whom were aged between 3 and 18 when they died. Around 200 flaked stone artefacts were also found. Palaeomagnetic considerations date the find to at least 700,000 years old; electron spin resonance dates the fossils and artefacts to between 857,000 and 780,000 years old; bones of extinct rodent species support this age; the excavators conservatively date the find to 800,000 years old.

However in 2007 a fragment of a mandible and an isolated lower left fourth premolar from the same individual were recovered from the TE9 layer at the nearby Sima del Elefante site. These have also been assigned to Homo antecessor and dating based on palaeomagnetism, biostratigraphy and cosmogenic nuclides suggests an age of 1.2–1.1 million years.

The tools found at the Gran Dolina are simple Mode 1 (Oldowan) technology, with no evidence of Acheulian hand-axes or cleavers characteristic of later African Homo ergaster or H. heidelbergensis.

One of the most significant features of the Gran Dolina TD6 find is that around 25% of the bones show signs of human-caused damage including chop and cut marks, peeling where bones have been broken and bent, and percussion marks where bones have been splintered for marrow extraction. All of which adds up to a compelling case for cannibalism. The extent of the damage suggests this was of a dietary rather than ritual nature, suggesting in turn nutritional stress.

Bermúdez de Castro and his colleagues argue against the currently popular view that hominids such as Mauer, Vertesszollos, Bilzingsleben, Arago, and Petralona, together with Bodo, Broken Hill 1, and Dali (among other middle Pleistocene fossils not considered to be H. erectus) belong to a single species, Homo heidelbergensis, that was ancestral to both modern humans and the Neanderthals. They argue that European middle Pleistocene fossils are ancestral only to the Neanderthals and that the Mauer mandible, the holotype for Homo heidelbergensis, shows clear derived Neanderthal traits, such as a large retromolar space, whereas teeth shape and morphology are indistinguishable from those of Neanderthals. They conclude that other than a European chronospecies, H. heidelbergensis should be rejected.

Dental and cranial features suggest Homo antecessor is close to Homo ergaster. While Homo antecessor has similarities to Homo heidelbergensis (i.e. proto-Neanderthals), it has more traits in common with modern humans than does Homo heidelbergensis, being for example relatively gracile, most similar to H. ergaster and modern humans but unlike H. heidelbergensis or the Neanderthals. On this picture, Homo antecessor evolved from Homo ergaster in Africa then spread via the Middle East to Europe where it evolved (via Homo heidelbergensis) into the Neanderthals. In Africa Homo antecessor evolved into Homo sapiens via such fossils as the Bodo and Kabwe skulls. The species Homo rhodesiensis or Homo helmei would have to be revived for these presumptive H. antecessor/H. sapiens transitional types, with H. heidelbergensis being a solely European transitional type between H. antecessor and the Neanderthals.

Neither this view nor Homo antecessor as a species is widely accepted. Many believe that H. antecessor is an ofshoot of Homo ergaster and that it died off without issue, possibly during the glacial periods of 800,000-600,000 years ago. Clearly further evidence is needed, from Africa in particular.